An ever increasing emphasis is being placed on systematic monitoring of environmental conditions in relation to ground and surface water resources. Examples of some situations when monitoring of conditions of a water resource may be desired include environmental monitoring of aquifers at an industrial site to detect possible contamination of the aquifer, monitoring the flow of storm water runoff and storm water runoff drainage patterns to determine effects on surface water resources, monitoring the flow or other conditions of water in a watershed from which a municipal water supply is obtained, monitoring lake, stream or reservoir levels, and monitoring ocean tidal movements.
These applications often involve taking data over an extended time and often over large geographic areas. For many applications, data is collected inside of wells or other holes in the ground. A common technique is to drill, or otherwise excavate, a number of monitoring wells and to insert down-hole monitoring tools into the wells to monitor some condition of water in the wells. Although such monitoring wells are sometimes very deep, they are more often relatively shallow. For example, a significant percentage of monitoring wells are less than 50 feet deep. The cost of drilling monitoring wells, even when relatively shallow, is significant, especially given that a large number of wells is often required. The down-hole monitoring tools also represent a significant cost.
One way to reduce costs is to use smaller diameter monitoring wells, because smaller diameter holes are less expensive to drill. One problem with smaller diameter holes, however, is that there is a lack of tools, and especially high performance tools, that are operable in the holes. For example, only tools with very limited capabilities are available for use in 1 inch diameter holes. There is a need for high performance tools for use in such small diameter holes.
One reason for the high cost of monitoring tools is that they use expensive components and designs that frequently require significant amounts of expensive machining. The tools often require the assembly of components to form a tool assembly for insertion into the monitoring wells, and significant manufacturing expense is often required to provide structures for coupling the components and for electrically interconnecting the components. These problems become even more pronounced when trying to provide a tool at reasonable cost for use in a small diameter monitoring well. Furthermore, assembly and disassembly of components of the down-hole tools frequently require the use of wrenches or other tools, and sometimes special tools. This complicates use of the down-hole monitoring tools, and providing features on the down-hole tools to accommodate tools required for assembly and disassembly often requires machining, which significantly adds to manufacturing costs. Furthermore, electrical interconnections between components typically require special keying of the components, or of the electrical connectors between the components, which result in difficulty of use and a possibility for tool damage or malfunction due to misalignment. There is a significant need for new designs for coupling and electrically interconnecting components to permit easier assembly of down-hole monitoring tools without the need for complex structures that are difficult to manufacture.
In addition to the high cost of monitoring wells and down-hole monitoring tools, a significant amount of ongoing labor is typically required to maintain the tools and to obtain and use data collected by the tools. For example, it is frequently necessary to have someone visit the monitoring wells at periodic intervals to make sure that the tools are still working and to obtain data collected by the tools. The data must then be analyzed for use. The frequency between visits to a well may be a function of a number of variables, such as the reliability of the tools, the frequency with which batteries need to be replaced, and the capacity of the tools to collect and store data. Moreover, many down-hole tools are difficult to service and must be returned to manufacturers or distributors for even relatively simple service tasks, such as changing batteries in the tool. There is a significant need for tools that require less attention and that are easier to service.
Many of the available down-hole monitoring tools also lack significant flexibility in the way they can be used. For example, many tool designs are not designed for remote communication, for networkability or for being powered by the variety of different power sources that may be suitable for different field applications. There is a need for down-hole monitoring tools having greater flexibility.